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Bacteriology

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Simmons Citrate Agar biochemistry test for Enterobacteriaceae

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Simmons Citrate Agar Simmons Citrate Agar  is an agar medium used for the differentiation of Enterobacteriaceae based on the utilization of citrate as the sole source of carbon.  Ingredients per liter of deionized water: Principle of Simmons Citrate Agar Uses of Simmons Citrate Agar 1.     It is used for the differentiation of Gram-negative bacteria on the basis of citrate utilization. 2.     Simmons Citrate Agar may be used to differentiate citrate-positive  Salmonella enteritidis  and members of  Salmonella  subgenus II, III and IV from the citrate-negative  Salmonella typhi, Salmonella paratyphi  A,  Salmonella pullorum  and  Salmonella gallinarum . 3.     Simmons Citrate Agar is primarily used to aid in the identification of Enterobacteriaceae. Uses include: Escherichia coli ...
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Triple Sugar Iron Test

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The Triple Sugar Iron (TSI) Test  To determine the ability of an organism to ferment glucose, lactose, and sucrose, and their ability to produce hydrogen sulfide. Principle The Triple Sugar Iron (TSI) test is a microbiological test named for its ability to test a microorganism’s ability to ferment sugars and to produce hydrogen sulfide. An agar slant of a special medium with multiple sugars constituting a pH-sensitive dye (phenol red), 1% lactose, 1% sucrose, 0.1% glucose, as well as sodium thiosulfate and ferrous sulfate or ferrous ammonium sulfate is used for carrying out the test.  . Due to the building of acid during fermentation, the pH falls. The acid base indicator Phenol red. is incorporated for detecting carbohydrate fermentation that is indicated by the change in color of the carbohydrate medium from orange red to yellow in the pres...
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Simmons Citrate Test

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Simmons Citrate Reaction It  used to differentiate among the Gram-Negative bacilli in the family Enterobacteriaceae. Principle  Citrate agar is used to test an organism’s ability to utilize citrate as a source of energy. The medium contains  citrate  as the sole  carbon source  and  inorganic ammonium salts (NH4H2PO4)  as the sole source of  nitrogen . Bacteria that can grow on this medium produce an enzyme,  citrate-permease , capable of converting  citrate  to  pyruvate .  Pyruvate  can then enter the organism’s metabolic cycle for the production of  energy . Growth is indicative of utilization of citrate, an intermediate metabolite in the  Krebs cycle . When the bacteria metabolize  citrate , the  ammonium salts  are broken down to  ammonia , which increases  alkalinity . The shift in pH turns the...
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